I just modded a NTSC Top Loader with the NESRBG modkit! However I've ran into a problem! The colors looks really strange in all games and in rare cases some tiles are missing like in the title screen of Ninja Gaiden for example.

The only thing that looks normal is the Powerpak menu, with correct colors, although they looked more dimmed compared to my high-def nes modded console.

I've tried the system through both a crt tv and through my OSSC with the same results on both.

What could be the cause of this? Is the PPU the culprit maybe? Bad caps? Something else I've might have missed? I've modded a NES before with the high-def nes without any issues like this so I'm not totally new to modding this kind of stuff.

I've tried to clean the 72 pin connector in the system, but not sure If I did it succesfully, it didn't look that dirty in the first place thou. Also tried to re-flow the solder on the 72 pin connector solder joints.

I'm definitely not an NESRGB expert, I only have a vague idea of how it works (using the EXT pins?). But that's never stopped me from speculating before.

The problem is with the background palette. Sprite palette looks fine. The missing graphics on the Ninja Gaiden title screen are almost certainly because the palette is the same as the background.

It doesn't narrow it down much, but the fault pretty much has to be with the NESRGB, or with the PPU. Nintendo never used the EXT pins for anything, and H revision chip is pretty late, I suppose it's conceivable that defective EXT pins would have been considered OK. I doubt that's the case though.

I'm definitely not an NESRGB expert, I only have a vague idea of how it works (using the EXT pins?). But that's never stopped me from speculating before.

The problem is with the background palette. Sprite palette looks fine. The missing graphics on the Ninja Gaiden title screen are almost certainly because the palette is the same as the background.

It doesn't narrow it down much, but the fault pretty much has to be with the NESRGB, or with the PPU. Nintendo never used the EXT pins for anything, and H revision chip is pretty late, I suppose it's conceivable that defective EXT pins would have been considered OK. I doubt that's the case though.

Ok, so the NESRGB board may be faulty? Or just not compatible with the H revision of the PPU?

tepples wrote:

If sprite palette is OK and background palette is busted, the connection of the composite output might be to blame.

Yeah, I also noticed the Sprites looked ok! What can be the cause of a broken composite output then? Faulty NESRGB board? Bad soldering? Bad PPU? I'm no expert at this.

Can it be a power issue maybe? I'm using the stock voltage regulator, should I use the one that comes included with the NESRGB instead?

His response to my question if he got it fixed was: "Yes, I've mod my french nes with the 5V mod and the etim board (taking off the avbox just keeping the plug). I have solder together the RGB ground, remove the 5V regulation.... but my universal wall charger was on 7.5V position.... With 5V the right color came back....﻿"

EDIT:

Another thing I've just realised!

I think I've got the NESRGB kit for the toaster NES, not the kit for the Top Loader/AV Famicom! They must have supplied me the wrong one! Is there any differences between hardwarewise with the NESRGB boards in those kits?

I ordered this kit way back, I haven't had time until now to assemble it, so didn't realise this until now!

My knowledge of EE stops at soldering, but... it looks to me like the BG is using the sprite palettes. That suggests the EXT pins are fine, and whatever the NESRGB uses to tell the sprites from the BG (the EXT pins don't carry that information) is wonky.

IIRC that's the composite on pin 21, and some sort of interposer to force the sprites to white and the BG to black (or vice-versa)? Like I said, I'm in over my head here.

My knowledge of EE stops at soldering, but... it looks to me like the BG is using the sprite palettes. That suggests the EXT pins are fine, and whatever the NESRGB uses to tell the sprites from the BG (the EXT pins don't carry that information) is wonky.

IIRC that's the composite on pin 21, and some sort of interposer to force the sprites to white and the BG to black (or vice-versa)? Like I said, I'm in over my head here.

Yeah that's how it works.

You could try hooking up the composite video output from the PPU (I think it's marked "PPUV" on the board). It should show white in the parts used for sprites and black in the parts used for the background. If that works, then you can look at the output of the comparator (marked EXT4-VIDEO here: https://etim.net.au/nesrgb/operation_block_diagram.png). It should alternate between 0/1 (background/sprites). In your case it looks like it might be stuck high for whatever reason.

My knowledge of EE stops at soldering, but... it looks to me like the BG is using the sprite palettes. That suggests the EXT pins are fine, and whatever the NESRGB uses to tell the sprites from the BG (the EXT pins don't carry that information) is wonky.

IIRC that's the composite on pin 21, and some sort of interposer to force the sprites to white and the BG to black (or vice-versa)? Like I said, I'm in over my head here.

Yeah that's how it works.

You could try hooking up the composite video output from the PPU (I think it's marked "PPUV" on the board). It should show white in the parts used for sprites and black in the parts used for the background. If that works, then you can look at the output of the comparator (marked EXT4-VIDEO here: https://etim.net.au/nesrgb/operation_block_diagram.png). It should alternate between 0/1 (background/sprites). In your case it looks like it might be stuck high for whatever reason.

Well, that sounds like a really good idea, I'm gonna try that out, if the comparator seems fine I'm gonna switch PPU with my other nes and see what that leads to! Thanks for enlighten me!

Well, I tried to use the PPUV output from the nesrgb-board with the exact same results as before, I also swapped PPU from my other hidef modded nes (Revision G PPU) with the exact same issues occuring when used in the NESRGB toploader, the H revision PPU from the top loader runs perfect in my hidef modded nes. I noticed thou (same with both PPU:s) that sometimes partial pixels of the logo i visible flickering in the invisible part of the ninja gaiden title screen, and quite common the game has a lot of solid white lines going vertically across the screen, I"m going to post some pictures a little later. The most strange thing I noticed thou is that in Mega Man 2, in Bubble mans stage for example, the background does not animate att all, it's just frozen still, togehter with many other kinds of animations in the game, is this some kind of CPU issue maybe? Only original game carts where used, no Everdrive etc.

Lastly another thing noticed was that sometimes the 72-pin connector is really sensitive so if I touch the game cartridge just a little I get a screen of garbled graphics, and sometimes at a later boot up of the console nothing happens at all when touching or even wiggling the cart back and forth a little. Maybe some power issue? Need to check the caps I think maybe.

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